Safety device for electric irons and the like



IN VEN TOR 4W ATTORNEY 2 Sheets-Sheet Ma ATTORNEY N. A. CURTISS SAFETY DEVICE FOR ELECTRIC IRONS AND THE LIKE Filed Jan. 22. 1924 Patented Oct. 13, 1925.

UNITED STATES PATENT FFCE.

NATHAN A. CURTISS, OF RAMSEY, NEVI JERSEY, ASSIGNOR TO MILLER REESE HUTCH- INSON, F NEJV YORK, N. Y.

SAFETY DEVICE FOR ELECTRIC IRONS .AND THE LIKE.

Application filed January 22, 1924.

T 0 all fio/710m t may concern.'

Be it known that I, NATHAN A. CUnTi'ss, a citizen of the United States, and residentof Ramsey, in the county of Bergen and tate of New Jersey, have invented certain new and useful Improvements in Safety De vices for Electric Irons and the like, of which the following is a specification.

My present invention is shown as embodied in an attachment designed to prevent overheating of flat-irons such as are commonly used for ironing fabrics, more specifically, fiat-irons in which the sole or ironing element is heated by means of an electrical resistance, energized by current. supplied from an outside source through flexible insulated conductors which are detachably connected to the iron during use, by means of frictionally engaging socket and plug terminals, one on the iron and the other on the end of the flexible conductor. However, various features of the invention are much broader and of more general application for various specifically different purposes and devices.

Various purposes or aspects of the invention include the following:

One is to provide means for ejecting the terminal box of a flexible conductor from its non-positive engagement with a cooperating terminal. Said cooperating terminal may be located on an electrical translating device which is movable within the range permitted by the flexible conductors. The translating device may be one which is liable to become overheated as a result of the electric current supplied thereto. The heat developmentmay be through the medium of an ohmic resistance, specifically designed for generating heat. Operation of the automatic ejector may be controlled by a heat sensitive element in heat-receiving relation to the ele` ment which is liable to overheating. The heat sensitive element may be one that is subject to tension or compression stress and capable of moving in response to said stress when the heat of the sensitive element exceeds a predetermined maximum.

Preferably, the heat sensitive element is a fuse conductively heated by contact with the heated body rather than by flow of electric current through the fuse itself.

The above more or less separate features or aspects of the invention may be of im- Seral No. 687,738.

portance individually or in selected groups or in the reverse order of the above statenient, according to the particular purpose 1n view.

Briefly and practically stated, the object of the specific embodimentabove is to provide an electric flat-iron with an automatic knock-out attachment that will eject the terminal connection whenever the iron gets too hot, the operation being controlled by a fuse metal structure element under stress so that it will rupture before it melts and which when ruptured may be. easily renewed, and the device re-set by the user:

The above and other features of my invention may be more readily understood from the following description in connection with the accompanying drawings, in which-- Fig. l is a side elevation of the rear portions of an electric flat-iron with my attachment applied thereto;

Fig. 2 is a rear elevation partly in section on the line Q-2, Fig. l;

Fig. 3 is a plan view of the under-side of the parts shown in Figs. 1 and 2, looking upward;

Figs. 4 and 5 are views similar to Figs. l and 2 but showing a modification.

In these drawings the attachment is shown as applied to a flat-iron of a model now purchasable in the market. The commercial article includes the heavy iron sole l cast integral with a` hollow portion 2 which contains the electrical heating resistance, not shown. The handle comprises the bail 3, secured to 2 in any desired way and the hand grip 4 mounted on bolt 5. Secured on this bolt 5 is a stand or bracket secured at G extending along the bail 3 to the bend 7, this horizontal at 8 forming a guard for the terminal block 9 of flexible conductor cord 10 which has slidable engagement with the plug terminals 1l which are mounted on the cast iron casing 2 which contains the heating resistance. At the end of the guard portion 8, there is an upwardly extending portion 1Q, forming one of the bearing points of the stand upon which the Weight of the iron rests when not in use. There is also a downwardly extending` wider portion extending to curve 13, which affords a long line bearing cooperating with l2 to constitute a triangular supporting base for the upwardly bent lugs or brackets 24, 24, rigidly supporting a shaft in suitable perforations 26. These may be pinched upon the shaft as the shaft does not have to rotate.

Mounted on the shaft 25 is a bellcrank, one arm of which 27 has its free end 28 extending between the terminal pins or plugs 11 in position for terminal block 9 to rest thereon, when the sockets thereof are fitted in frictional engagement with said pins 11. This knockout arm is preferably covered with insulation to prevent danger of shortcircuit in case `o accidental contact with pins l1, while the current is flowing therein.

The knock-out arm is spring pressed upwardly by means .of a helical torsion spring 30 having one end 31. in anchored or thrust relation to bracket member 14 and the other end 32 enga ing a suitable notched tail projection 33 wic is integral with the hub of the bell-crank. The other arm 4() of the bell-crank extends downward through slot 41 in 14 and 20. When the spring 30 is tensed and the knock-out 27 in the lowermost position shown in the drawings, the arm is in operative relation to be held by detent 42, which is one end of a smalier bellcrank pivoted on stud-bolt 13 and the other arm 44 extends towards the rear edge 45 of the sole 1 of the Hat-iron. This bell-crank is a sort ot trigger that holds the knock-out lever in the retracted position and the trigger is in turn held b a link oi fusible metal resting flat against said surface. The link is anchored at one end by a stud 51 engaging a perforation in one end of the link. This stud is an extension of a sliding bolt 52 which is rigidly guided tor movement in a plane perpendicular to the link by means of a guide 53. The bolt is provided with an integral collar 54 which is pressed downward upon the link to keep it in close contact with the hot iron by means of spring 55. The up er end of the spring is provided with a nurled head 56. whereby the bolt may be retracted. A similar stud 61 engages a similar hole in the other end of the link. The latter stud being on the pivoted bell-crank arm 44, must be rotated into engagement with the hole in the link before the stud 5.1.. is snapped into the hole at the other end of the link.

The link 50 is made of any desired fusible metal and it may be a lead alloy composition such as is used for ordinary electrical fuses,

which it will rupture under the stress aplied by a spring 30 operating through be crank arm 40 and trigger bell-crank 42, 44..

For a fiat-iron the rupturing temperature may be predetermined quite accurately' for a narrow range anywhere between 350 and 500 degrees.

Having the link under stress so that it will rupture instead of melting is o1" piactical advantage because there is no scattering of the molten metal upon the fabrics which are being ironcd.

The parts being set in the above described position, the operator uses the iron as usual, attaching or detaching the plug 9 by hand in the usual way and using the bearing points 12, 13 of the bracket for the hot irqn to rest upon when not in use. It is only 1f and when the iron exceeds the predetermined temperature that the linlf 50 ruptures. This releases the trigger, which releases the arm 40 and permits the spri 30 to sna the li'nock-out lever 27 up to rtige osition s lown in dotted lines in Flg. 1. s referably, the length and throw of the lever -is such as project the block 9 at considerable velocity. The adjacent surface cf the bracket surface is a stop for the lever and the impact is violent enou ,h to give a sound serving as an alarm signal! clearly audible at a considerable distance from the iron. Moreover, in the proportion shown, the kick or reaction of the snapping hammer is sufficientto throw the iron down to the position in Fi 1 if it happens to be resting on the brac et bearing points 12, 13.

In Figs. 4 and 5 the construction of the fiat-iron, its switch the attaching bracket and the knock-out hell-crank are the same as in the preceding figures, but the means for holding the knock-out in the set position is different. Here the lower end of lever 40 is provided with a detent 42, which applies a thrust to the heat sensitive element. In the form shown, the heat sensitive element comprises a tubular member in telescoping relation with a piston member 71. A surface as at 72 fits a recess 73 in the solo of the iron and one end of the piston member 71 ervgliges the conical bottom 74 of the recess. e fuse is held in the extended position shown in Fig. 4 b simply sweating or soldering the sliding joint at 75. While the detent 42 may be integral with the lower end of arm 40, I have shown it as bei in the form of a latch on a bolt 80, backed y a spring 81 and slidably held in longitudinal recess 82 by a pin 83 which plays in slot 84. This permits the detent 42 to retreat and snap behind the heat sensitive thrust member, with more velocity and to `a greater depth than is easily obtainable when 42 is integral with 40.

Obviously, each sensitive thrust member, 70, 7l, may be an integral piece of fusible metal, in which case the tube and piston construction is unnecessary and many varied forms are possible for said thrust meinber.

In both forms of the device the knock-out may be reset and reloaded simply by pushing down the plug 9 and inserting the fuse element. In the sliding detent form shown in Figs. 4 and 5 no other precaution need be taken but in the forms shown in Figs. l, 2 and 3, the lug 61 has to be rotated into the hole in one end of the link before the lug l is snapped into the hole in the other end of the link.

I claim:

1. A heat generating electrical device having a fixed terminal thereon and a flexible conductor having a terminal non-positively engaging said fixed terminal, in combination with a knock-out lever rockingly mounted on the device with one end projecting between said terminals, an actuating spring for the lever and a trigger device for restraining and releasing the lever.

2. An electrically heated flat-iron, having a pair of .fixed terminals spaced apart in the rear of the handle and a flexible conductor having a terminal block slidingly engaging said fixed terminals, in combination with a knock-out lever projecting between said fixed terminals and means for actuating said lever to eject said terminal block, said means including a torsional actuating spring, a detent, and a fusible metal link in contact with the flat-iron, restraining release of said detent.

An electrically heated flat-iron, having a pair of fixed terminals spaced apart in the rear of the handle and a flexible conductor having a terminal block slidingly engaging said fixed terminals, in combination with a knock-out lever projecting between said fixed terminals and means for actuating said lever to eject said terminal block, said lever being one arm of a bell-crank pivoted at the rear of the flat-iron and actuated by a spring, another arm of the bell-crank being restrained by a detent which is restrained by a fusible metal element which is in contact with the rear end of the sole of the flat-iron.

Il. An electrically heated flat-iron, having a pair of fixed terminals projecting upwardly behind the handle and a flexible conductor having a terminal block having t pair of sockets slidingly engaging said fixed terminals, in combination With a knock-out lever projecting between said fixed terminals and means for actuating said lever to eject said terminal block, said means including an actuating spring, a spring urged detent,

tor having a terminal block having a pair of sockets slidingly engaging said fixed terminals, in combination with a knockeont lever projecting between said fixed terminals and means ttor actuating said lever to eject said terminal block` said lever being one arm of a bell-crank pivoted at the rear of the flat-iron and actuated by a tarsion spring, another arm of the bell-crank being restrained by a detent which is restrained by a fusible metal element which is in contact with the rear end of the sole of the flat-iron.

(S. An electrically heated flat-iron, having a pair of fixed term'znais projecting upwardly in the rear of the handle, a stand secured as u` guard exten-'cling over said termii'nzls and having a wide horizontal portion adjacent lthe sole of the iron; and a flexible conductor und terminal block insertuble through said guard and slidingly engaging said fix-id terminals, in combination with an attachment' secured to said horizontal portion of the stand, including a suitable support having mounted thereon a knock-out projecting between said fixed terminals and means for actuating said lever to eject said terminal block.

T. An electrically heated flat-iron, having a pair of fixed terminals projecting upwardly in the of the handle, a stand secured as a guard extending over said terminals and having a wide horizontal portion adjacent the sole of the iron; and a flexible conductor and terminal block insertable through said guard and slidingly engaging said fixed terminals, in combination with un attachment securedto said horizontal portion of the stand, including a suitable support having mounted thereon a knock-out lever proj ecting between said fixed terminals und means for actuating said lever to eject said terminal block. said means including an actuating spring, a detent, and a fusible metal link in contact with the flat-iron` restraining` release of said detent.

S. An electrically heated flat-iron, having a pair of fined terminals projecting upwardly in the rear of the handle. a stand secured as a guard extending over said terminals and having a with` horizontal portion adjacent the sole of the iron; and a fl xible conductor and terminal block insertable through said guard and slidingly engaging said fixed terminals, in combination with an attachment secured to said horizontal portion of the stand, including a suitable support having mounted thereon a knock-ont lever projecting between said fixed terminals and means for actuating said lever to eject conductor and terminal block insertable through said guard and slid ngly engaging said lixed terminals, in combination with an attachment secured to said horizontal portion of the stand, including a suitable fu port having mounted thereon a shaft, a be crank on the shaft having a knock-out arm projecting between said fixed terminals, s, spring encircling said shaft and pressin said knock-out arm upwardly, a down ar ly projecting arm for said bell-crank, a detent engaging the latter and restrained by a fusible metal element which is in contact with the rear end of the sole of the flat-iron.

Signed at New York in the county of New York and State of New York this 21st day of January, A. D. 1924.

NATHAN A. CURTISS. 

